PROJECT SUMMARY: The Columbia Center for Children?s Environmental Health (CCCEH) requests support to maintain retention and engagement of its unique environmental cohorts, enhance basic laboratory and data management resources, increase community outreach, and set the stage for new partnerships and training opportunities to evaluate cumulative oxidative damage from prenatal exposure to mixtures of environmental pollutants. Currently, over 1,000 children are enrolled in the CCCEH cohorts, including the Mothers and Newborns cohort, the Sibling/Hermanos cohort, and the Fair Start cohort; we expect that we will have a total enrollment of 1,500 children by 2023. The CCCEH cohorts are comprised of mothers and children who are low income and minority (largely African-American and Latino). Therefore, it is of critical importance to retain these participants, their associated biorepositories, and the environmental health data they have provided through increased engagement activities, more laboratory resources, and enhanced data management, preparation, and sharing. Impressively, over the past 20 years, the Center has collected over 4,100,416 for 31,742 variables and 8,478 standardized derived variables. The exposures studied in these cohorts include diverse toxic pollutants and chemicals, including polycyclic aromatic hydrocarbons (PAH), phthalates, pesticides, bisphenol A (BPA), environmental tobacco smoke (ETS), and polybrominated diphenyl ethers (PBDE) flame retardants. The Center has also collected a wealth of outcome data from anthropometric measures, neurodevelopmental assessments, magnetic resonance imaging (MRI), and health records. The support will facilitate the Center?s outreach efforts to guide behaviors and inform policies to reduce exposures of pregnant women and children to toxic chemicals and pollutants. It will lay the groundwork for new collaborations across cohorts by incorporating novel biological measures that can provide new insight on the mechanisms of exposure-related disease. To develop a novel biomarker for assessing cumulative damage in mtDNA, the Center will integrate information from high-throughput screening programs (such as Tox21 and ToxCast?) to inform mixture models based on mitochondrial toxicity. The Center will also develop a new inter-institutional collaboration with Mount Sinai School of Medicine that will compare mtDNA measures in our CCCEH cohorts with the same measures in their birth cohort from Mexico City. Given the urgent need to prevent environmentally related diseases and neurodevelopment disorders in children, strong infrastructure support is warranted to maintain and preserve our Center?s unique resources, prepare for future research directions, and ensure effective communication of our findings.